Supercharger



Feb. 18, 1958 Filed Sept. 8, 1955 J. R. SHIELDS 2,823,851

SUPERCHARGER 3 Sheets-Sheet 1 J Ewe/V6118 Feb. 18, 1958 J. R. SHIELDS 2,323,851

SUPERCHARGER Filed Sept. 8, 1955 3 Sheets-Sheet 2 Feb. 18, 1958 .1. R. SHIELDS 2,

SUPERCHARGER Filed Sept. 8, 1955 L s sheetssheet s EN TOR. \lvma Gm-w;

United b tates l atent @fihce 2,823,851 Patented Feb. 18, 1958 SUPERCHARGER James R. Shields, Penn Township, Pa., assignor to Elliott Company, a corporation of Pennsylvania Application September 8, 1955, Serial No. 533,058

7 Claims. (Cl. 236-416) This invention relates to superchargers in which air compressors are driven by gas turbines, and more particularly to the relation of the compressor outlet to the turbine inlet. V

Mechanical and operating design problems of such superchargers generally require a construction that will minimize high temperature distortions, eliminate high pressure and high temperature seals for rotating shafts, eliminate high temperature insulation and permit the location of bearings away from high temperature zones. One obvious manner of accomplishing these objectives is to mount the compressor and turbine blading on a single shaft, with the high pressure ends of the two groups of blades near the center of the shaft. Such a construction needs only two outboard bearings, and they are located in accessible low temperature and low pressure areas. This arrangement also minimizes thrust loads due to aerodynamic forces acting on the compressor and turbine blading. However, for the necessary aerodynamic eiiiciencies, a discharge diifuser is required for the compressor, and a slowly accelerating inlet casing or infuser for the gas turbine. Heretofore, ithas been necessary to have a long length of shaft between the two groups of blades to accommodate the diffuser and infuser, resulting in the loss of many of the advantages of the single shaft construction. it also has generally been impossible to obtain a stiff shaft rotor design with such a long shaft.

It is among the objects of this invention to provide a single shaft supercharger, in which the rotor shaft is short enough to have the necessary stiffness, in which the infuser-diifuser assembly is supported in an improved manner, in which the outer shell is subjected only to the low temperature compressor discharge air, and in which the infuser operates only under the pressure difference between its gas and air sides.

In accordance with this invention, a relatively short rotatable shaft is supported by bearings at its opposite ends. Turbine blades are carried by the shaft near one end, while compressor blades are carried by the shaft between its opposite end and the turbine blades. A compressor housing surrounds the compressor blades and has an air inlet near the end of the shaft that is closest to the compressor blades. The housing also has an annular air outlet near the turbine blades. A turbine housing surrounds the turbine blades and has a gas outlet near the adjacent bearing. It also has an annular inlet near the compressor outlet. An infuser is connected with the turbine inlet and includes a plurality of circumferentially spaced tubes. An annular casing surrounds the rotor shaft between the infuser and the compressor housing inlet and has an outlet communicating with the outer end of the infuser. Connected with the compressor housing outlet is a diduser, which includes a plurality of circumferentially spaced tubular passages extending outward between the infuser tubes. A. shell encloses the annular casing and the diffuser for receiving compressed air from the latter. The shell is provided with an outlet and also with a hot gas inlet. The shell inlet is connected with Fig. 2 is a greatly reduced view of the turbine end of the supercharger;

Fig. 3 is a central longitudinal section through the supercharger; and

Figs. 4 and 5 are cross sections taken on the lines iV--lV and V--V, respectively, of Fig. 1.

Referring to Fig. 3 of the drawings, a short horizontal rotor shaft 3. is rotatably supported at its opposite ends by suitable bearings 2 and 3. This shaft carries two groups of blades that can be attached to the shaft in any suitable manner (not shown), a compressor group 4 and a turbine group 5. The turbine blades are attached to the end of the shaft next to bearing 3 and extend inwardly along the shaft only a short distance. Spaced a little ways from these blades are the compressor blades, which extend along the shaft to its opposite end.

The compressor blades are surrounded by a long cylindrical housing 1'', in which the stationary compressor blades 8 are mounted. The inlet bell 9 leading into the compressor housing is disposed in an inlet shell 10, which surrounds and supports the adjacent shaft bearing 2. The outer wall of the shell is provided with an inlet 11 for the air that is to be compressed. The opposite end of the compressor housing has an annular outlet that forms the entrance to a difiuser 12 encircling the shaft.

The turbine blades are surrounded by a short housing id that supports the usual stationary blades 15. This housing is supported by an encircling partition Wall 16 that extends outward to a central shell 1'7 that connects inlet shell It with an outlet shell 18 which surrounds and supports bearing 3. The outer end of the turbine housing 14 is connected with a discharge bell 19 that empties into the outlet shell, which is provided with an outlet 20 for turbine exhaust gases.

The annular inlet of the turbine is connected with an infuser 22. This infuser has a flaring annular portion 23, the outer end of which is welded to concentric internal and external rings 24 and 25. Bolted to these rings is a radial plate 27 that is provided with a plurality of circumferentially spaced triangular openings 28. Short tubes 29 that are triangular in cross section have their inner ends welded to the plate around the openings. These circuinferentially spaced tubes are inclined outward and have their outer ends secured to a radial end wall of an annular casing 36 that encircles the compressor in spaced relation with it. The casing end wall is provided with triangular openings which open into the tubes. The casing is supported by the tubes.

The compressor diffuser also includes circumferentially spaced tubes or, more correctly, tubular passages, and these passages extend more or less radially outward between the infuser tubes 29. In fact, two opposite walls of each passage are formed by the sides of two of the infuser tubes. The other two walls of the tubular passage are formed by curved plates 32 and 33 welded to the same two infuser tubes. Consequently, the outlet of the diifuser is around the infuser tubes, because the two sets of tubes cross each other. Compressed air leaving the diifuser enters central shell 17, from which it is led away to the desired location through an outlet 34 in the shell.

The annular casing 3b is provided with a radial inlet conduit 36 that extends out into a short inlet conduit 37, with which the encircling central shell 17 is provided. To seal the space between these two conduits, the outer end of the inner conduit 36 is encircled by a groove, in which an expansiblc sealing ring 38, like a piston ring, is mounted. This ring engages the inside of the outer conduit 37 and can slide back and forth in it as the casing expands and contracts, yet compressed air will not escape from the shell between the two conduits.

In the operation of this supercharger, hot gases enter casing 30 through conduit 36 and then flow through infuser 22 to the turbine. The energy in the gases drives the turbine and thereby drives the compressor. Air is drawn into the compressor through inlet l]; and inlet hell 9, and compressed air is discharged from the cornpressor through the difiuser 12. The compressed air flows out between infuser tubes 29 and then out of the central shell outlet 34.

Due to the infuser and diffuser tubes crossing one another, inlet casing 30 can encircle the compressor instead of having to be located between the diffuser and infuser. A great advantage of this is that rotor shaft 1 can be made a great deal shorter than otherwise would be the case. That means that the shaft can have the necessary stiffness and that the length of the supercharger can be reduced materially. Another advantage of my construction is that the inlet casing 3th is supported only by the infuser and therefore floats in the central shell, so that thermal expansion problems are eliminated as far as it is concerned. Such problems arising from differences in expansion between the infuser and difiuser can be avoided by spacing the annular inner portion of the diffuser slightly from the infuser tubes and plates 32 and 33. Since casing 30 and the infuser operate only under the relatively small pressure difference between their gas and air sides, they can be made of very thin and flexible metal to withstand temperature expansions and to permit accurate location of the turbine nozzle ring relative to the turbine rotor blading. The combination of the diffuser and infuser which allows the gas turbine inlet casing to be flexibly supported inside the compressor casing eliminates the need for external high temperature insulation of this part. The discharge air from the compressor cools the gas turbine casing without heat loss from the system, and the pressure casing need only be insulated against the considerably lower temperatures of the discharge air and turbine exhaust gases.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, Within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A supercharger comprising a rotatable shaft, bearings supporting the opposite ends of the shaft, turbine blades carried by the shaft adjacent one end, compressor blades carried by the shaft between its opposite end and the turbine blades, a compressor housing surrounding the compressor blades and having an air inlet near said opposite end of the shaft, said housing having an annular air outlet near the turbine blades, a turbine housing sur rounding the turbine blades and having a gas outlet near the adjacent bearing, said turbine housing having an annular inlet near said air outlet, an infuser connected with said turbine inlet and including a plurality of circumferentially spaced gas tubes, an annular casing surrounding the shaft between the infuser and said compressor housing inlet and having an outlet communicating with the 'outer end of the infuser and also having an inlet, a diffuser connected with said compressor outlet and including a plurality of circumferentially spaced tubular air passages extending outward between the infuser tubes, a shell enclosing said casing and diffuser for receiving compressed air from the latter and having an outlet and a hot gas inlet, and means connecting said shell inlet with said casing inlet.

2. A supercharger according to claim 1, in which said annular casing floats in said shell.

3. A supercharger according to claim 1, in which said annular casing is supported only by the infuser in spaced relation with said shell and compressor housing.

4-. A supercharger according to claim 1, in which the tubular passages of the diffuser are formed between plates disposed between and supported by the infuser tubes, said plates being separate from the portion of the diffuser at their inner ends.

5. A supercharger according to claim 1, in which said inlet connecting means is a radial conduit joined to said casing inlet and extending loosely through said shell inlet, and a sealing ring encircles said conduit in sealing engagement therewith and slidably engages the wall of the shell inlet.

6. A supercharger comprising a rotatable shaft, bearings supporting the opposite ends of the shaft, turbine blades carried by the shaft adjacent one end, compressor blades carried by the shaft between its opposite end and the turbine blades, a compressor housing surrounding the compressor blades and having an air inlet near said opposite end of the shaft, said housing having an annular air outlet near the turbine blades, a turbine housing surrounding the turbine blades and having a gas outlet near the adjacent bearing, said turbine housing having an annular inlet near said air outlet, an infuser connected with said turbine inlet and supported by the turbine housing, the infuser having an annular portion supporting at its outer end a radial plate surrounding said shaft and provided with a plurality of circumferentially spaced openings, the infuser also including a plurality of gas tubes extending from said openings away from its annular portion, an annular casing surrounding the shaft between the infuser and said compressor inlet and having circumferentially spaced outlets communicating with the outer ends of the infuser tubes and also having an inlet, a diffuser connected with compressor outlet and including a plurality of circumferentially spaced tubular air passages extending outward between the infuser tubes, a shell enclosing said casing and diffuser for receiving compressed air from the latter and having an outlet and a hot gas inlet, and means connectingsaid shell inlet with said casing inlet.

7. A supercharger comprising a rotatable shaft, bearings supporting the opposite ends of the shaft, turbine blades carried by the shaft adjacent one end, compressor blades carried by the shaft between its opposite end and the turbine blades, a compressor housing surrounding the compressor blades and having an air inlet near said opposite end of the shaft, said housing having an annular air outlet near the turbine blades and concentric with the shaft, a turbine housing surrounding the turbine blades and having a gas outlet near the adjacent bearing, said turbine housing having an annular inlet near said air outlet and concentric with the shaft, an infuser connected with said turbine inlet and including a plurality of circumferentially spaced gas tubes extending toward the compressor, and a diffuser connected with said compressor outlet and including a plurality of circumferentially spaced tubular air passages extending outward between the infuser tubes in the area between the turbine and compressor housings.

References Cited in the file of this patent FOREIGN PATENTS 559,839 Great Britain Mar. 7, 1944 583,500 Great Britain Dec. 19, 1947 624,273 Great Britain June 1, 1949 

